Reaction Rates Part 1 - How to Calculate the Average Reaction Rate from Graphs and TOV

To calculate the average reaction rate in chemistry, you need to know the change in concentration of a reactant or product over a specific time interval. The average reaction rate is expressed as the change in concentration per unit of time.
Here's the general formula for calculating the average reaction rate:
Average Reaction Rate = (Change in Concentration of Reactant or Product) / (Time Interval)
Here are the steps to calculate the average reaction rate:
Determine the chemical reaction of interest and identify the reactant or product for which you want to calculate the average rate.
Measure the initial concentration (C_initial) and final concentration (C_final) of the reactant or product. Make sure the concentrations are expressed in the same units (e.g., molarity, moles per liter).
Determine the time interval (Δt) over which you want to calculate the average reaction rate. This time interval should be specified in seconds, minutes, or any time unit you choose.
Use the formula to calculate the change in concentration:
Change in Concentration = C_final - C_initial
Plug the values into the formula for the average reaction rate:
Average Reaction Rate = (Change in Concentration) / (Δt)
Calculate the result. The units for the average reaction rate will depend on the units of concentration and time you used in the calculation. It could be expressed as moles per liter per second (M/s), moles per liter per minute (M/min), or any other appropriate unit.
Here's an example:
Suppose you have a chemical reaction where the concentration of reactant A decreases from 0.2 M to 0.1 M over a 10-second time interval. You can calculate the average reaction rate as follows:
Change in Concentration = C_final - C_initial
Change in Concentration = 0.1 M - 0.2 M = -0.1 M
Average Reaction Rate = (Change in Concentration) / (Δt)
Average Reaction Rate = (-0.1 M) / (10 s) = -0.01 M/s
So, the average reaction rate for this reaction is -0.01 M/s, indicating that the concentration of reactant A is decreasing at a rate of 0.01 moles per liter per second. The negative sign indicates that the concentration is decreasing with time as the reactant is being consumed.